Table 2 Variables measured in the four head and mandibular positions and statistical analysis.

From: Mandibular advancement impairs swallowing ability more than head extension but less than mouth opening in the supine position

Variables

Position

F value

P value

Neutral

Extension

Opening

Advancement

Volume of residual water, ml

0.24 ± 0.37

1.11 ± 1.14

7.95 ± 2.61

4.73 ± 3.46

33.728

<0.001*

Peak amplitude of SH EMG

     Raw value, mV

0.34 ± 0.12

0.39 ± 0.14

0.26 ± 0.15

0.30 ± 0.13

3.783

0.019

     Normalised value, %

100

123.5 ± 53.4

79.8 ± 42.5

96.0 ± 52.7

3.916

0.016

Duration of SH EMG activity, s.

1.34 ± 0.35

1.56 ± 0.33

1.23 ± 0.31

1.28 ± 0.36

4.095

0.013

  1. Data are expressed as mean ± standard deviation. Neutral, Neutral position; Extension, Head extension position; Opening, Mouth opening position; Advancement, mandibular advancement position; SH EMG, Electromyogram of the suprahyoid muscles. *Data were corrected using the Greenhouse–Geisser method (Mauchly’s sphericity test was used to confirm the sphericity of the data; in cases in which the sphericity was violated, the data were corrected using the Greenhouse–Geisser method).
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